A high-temperature autoclave was used to grow CO2 corrosion-product films on P110SS steel specimens while the surface of the specimens was continuously subjected to tensile stress in a four-point bending jig; the autoclaving times were 6, 18, 36, and 72 h. A scanning electron microscope was used to observe the surface topography of the corrosion-product films formed on the P110SS steels. An X-ray diffraction was used to analyze the phase compositions of the corrosion products. The electrochemical performance of the films was investigated using electrochemical impedance spectroscopy and potentiodynamic polarization curves. The results showed that tensile stress could hinder the formation of corrosion-product films; the integrity and compactness of the films worsened, but the phase compositions of the films did not change. The applied tensile stress resulted in a smaller grain size of the corrosion-product films, and the grain boundaries increased. In addition, owing to the induced tensile stress, the charge transfer resistances decreased, and the corrosion current densities increased for the P110SS steels with corrosion-product films in a 3.5 wt.% NaCl solution saturated with CO2.
Corrosion product films were formed on P110 casing steels by high-temperature and high-pressure autoclave in a CO 2 environment induced by tensile stress. The effects of applied tensile stress on the protection characteristics and electrochemical performance of the corrosion product films were investigated. Scanning electron microscopy, X-ray diffraction, and electrochemical workstation were employed to analyse the surface morphology, phase composition, electrochemical impedance spectroscopy, potential dynamic polarisation curve and Mott-Schottky curve of the corrosion product films formed on P110 casing steels in 3.5 wt.% NaCl solution of saturated CO 2 environment. Results showed that the integrated corrosion product films formed on P110 casing steels as induced by tensile stress, and the phase of these films was not changed. The applied tensile stress can result in smaller grain size of corrosion product films, increased grain boundaries and appearance of micro channels. Consequently, the corrosion potential showed a negative shift and the corrosion current density was considerably increased. Meanwhile, the charge transfer resistance decreased, and the concentration of carrier increased owing to the P110 corrosion product films in 3.5 wt.% NaCl solution filled with saturated CO 2 .
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